Apparatus for automatically filling conduit strings



June 19, 1956 J. F. MUSE APPARATUS FOR AUTOMATICALLY FILLING CONDUI T STRINGS Filed April 27, 1953 2 Sheets-Sheet 1 ITO/4N E Muss,

INVENTOR.

A rroewE Y5 June 19, 1956 J. F. MUSE 2,751,021

APPARATUS FOR AUTOMATICALLY FILLING CONDUIT STRINGS Filed April 27, 1953 2 Sheets-Sheet 2 5 b i I IN V EN TOR.

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A TTOENEYS United States Patent Ofi ice 2,751,021 Patented June 19, 1956 APPARATUS FOR AUTOMATICALLY FILLING CONDUIT STRING John F. Muse, Montcbello, Califi, assignor to Baker Oil Tools, The, Vernon, Caliii, a corporation of California Application April 27, 1953, Serial No. 351,395

12 Claims. (Cl. 166-225) The present invention relates to subsurface well apparatus, and more particularly to apparatus for controllably filling a conduit string, such as a string of easing or drill pipe, with the fluid in the well bore as it is lowered therewithin.

Conduit strings, such as casing or drill pipe strings, oftentimes embody an upwardly closing back pressure valve to preclude upward or return flow of fluid into the string. Such back pressure valves are necessary, but they need not be operable at all times. Since they prevent upward flow of fluid in the conduit string, they maintain the latter in an empty state while it is being lowered through the fluid in the well bore. This necessitates the filling of the conduit string from the top of the hole, which is a time consuming operation.

Apparatus has been proposed for allowing the conduit string to fill automatically with the well bore fluid, despite the presence of a back pressure valve. Such apparatus, although operating effectively, is relatively complex and costly to manufacture. Moreover, it may have its parts, including the back pressure valve, eroded or cut by the well bore fluid as the latter flows upwardly into and within the conduit string.

Accordingly, it is an object of the present invention to provide apparatus to be incorporated in a conduit string and embodying a back pressure valve, which allows the conduit string to fill automatically with the well bore fluid as it is lowered in the well bore, the apparatus being comparatively simple, relatively shorter in length, and economical to manufacture.

Another object of the invention is to provide back pressure valve apparatus of the character indicatedgin which erosion or fluid cutting of the parts is greatly minimized. More specifically, the back pressure valve is held wide open during the lowering of the conduit string in the well bore, being disposed substantially completely out of the path of the fluid flow upwardly in the conduit string, thus precluding the fluid from acting onthe valve and insuring its leakproof engagement with its companion seat when it is later allowed to function.

A further object of the invention is to provide an apparatus to be incorporated in a conduit string, that allows fluid in the well bore to fill the conduit string to a predetermined lower level than the hydrostatic head of fluid in the well bore surrounding the conduit string during lowering of the latter in the well bore, and in which the well bore fluid can continue to rise in the conduit string to the same level as the fluid externally of the conduit string in a relatively slow manner, inorder to prevent the fluid from flowing over the top of the conduit string. Thus, the fluid can fill the conduit string rapidly up to a level lower than the external fluid level, which precludes overflowing of the fluid at the top of the conduit string. The subsequent completion of the conduit filling at a slow rate results in the lack of the conduit string overflowing even when completely filled. This invention possesses many other advantages, and

has other objects which may be made more clearly tip parent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Figure l is a longitudinal section through a well apparatus embodying the invention, with the filling valve open;

Fig. 2 is a view similar to Fig. 1, disclosing the filling valve closed;

Fig. 3 is a view similar to Fig. 1, showing the filling valve rendered ineffective and the back pressure valve allowed to close;

Fig. 4 is a cross-section, taken along the line 4-4 in Fig. 3.

Fig. 5 is a cross-section, taken along the line 55 on Fig. 3.

The apparatus A disclosed in the drawings is designed to form part of a string of well casing B to be run in a well bore. As specifically illustrated, it is embodied in a casing shoe forming the lower terminus of the casing string. However, it is to be understood that this apparatus could also be incorporated in a casing string at an intermediate point along its length, in which event it would be considered to be a casing collar. In addition, the apparatus A could be incorporated at the desired point in a string of drill pipe, or the like.

The apparatus includes an outer tubular member 10 having an upper threaded box 11 for threaded attachment to the lower end 12 of an adjacent casing section B. The tubular member 10 has a cementitious plug 13 cast therein, ribs 14 on the plug being formed in the casting operation by external grooves 15 in the tubular member, for

the purpose of inseparably uniting the parts against relative movement.

The lower end 16 of the cementitious plug is rounded, to provide a guiding nose for facilitating passage of the casing string B through obstructions and restrictions in the well bore as it is being lowered therewithin.

The cementitious plug 13 has a central passage 17 therethrough. This passage is surrounded by a valve seat 18 cast within the plug which is engageable by a back pressure valve element 19, disclosed as being in the form of a flapper valve having an ear 20 mounted on a pivot pin 21 extending between spaced lugs 22 depending from the valve seat 18. This valve element 19 is normally urged in an upward direction, into engagement with its companion seat 18, by a spring 23 wound around the hinge pin 21, one arm 24 of the spring bearing against the valve seat 18 and the other arm 25 bearing against the flapper valve head 19 itself. For the purpose of precluding leakage between the valve head 19 and its companion seat 18, aseal ring 26 may be provided in a suitable ring groove 27 in the seat 18, which is adapted to engage the periphery of the valve head 19.

' The valve seat 18 actually forms part of an upper housing section 28 depending from the seat and piloted within a lower housing section 29. Both of these housing sections 28, 29 are inseparably united to the cementitious plug 13 by means of external grooves 30 receiving ribs 31 in the cementitious plug. The upper housing section engagement with the seat 18 during lowering of the casing string through the fluid in the well bore, for the purpose of allowing the well here fluid to flow upwardly through the apparatus and into the casing. It is also desired to controllably fill the casing string with the well bore fluid up to a predetermined level, which may preferably be less than the level of the fluid externally of the casing string. To accomplish these objectives, a valve device C is embodied in the tubular member below the back pressure valve 18, 19, this device including and being disposed within the lower housing section 29.

p The valve device for controllably filling the well bore fluid includes a tubular valve member 33 that is slidable along the wall of the lower housing section 29. This tubular member has an upwardly projecting tubular portion or skirt 34 adapted to engage the flapper valve head 19 and maintain it in open position within the upper housing window 32, and substantially completely to one side of the path of fluid flow through the apparatus. The sleeve valve member 33 is movable upwardly within the lower housing section, such upward movement being determined by engagement of a shoulder 35 thereon with an inwardly projecting shoulder 36 formed at the lower end of the upper housing section 28. Downward movement of the valve member 33 within the lower housing section is at first limited by engagement of its inner edge 37 with a valve seat 38 releasably connected to the lower housing section 29. When so engaged with the valve seat, the upper extension 34 of the slidable valve member 33 is still engaged with the flapper valve head 19 to maintain it in open position. However, when the valve seat 38 is released and shifted downwardly, the slidable sleeve valve 34 can move downwardly to a position in which a lower intermediate shoulder 39 thereon engages a companion internal shoulder 40 in the lower housing section. When in this position, the valve extension 34 moves out of engagement from the flapper valve head 1? and allows the spring 23 to shift the latter to its closed position in engagement with its companion seat 18.

The valve seat 38 is held initially in a fixed position within the lower housing section 29, the sleeve valve 33 being shiftable upwardly and downwardly away from and into engagement with the enlarged head portion 41 of the seat. The seat has 21 depending stem portion 42 that extends through the central hub 43 of a spider 44, which is connected to the lower housing section 29 by means of a plurality of radially arranged and circnmferentially spaced ribs 45. The seat stem 42 is initially and releasably secured to the spider hub 43 by one or more shear pins 46 extending transversely through the hub 43 and into companion holes 47 in the stern. These pins are prevented from displacement from their assembled position by an encompassing retainer sleeve 48 engaging a downwardly faeing shoulder 49 on the hub, the sleeve being prevented from dropping down along the hub 43 by engaging the head of a screw 59 threaded transversely into the hub 43.

The fluid in the well bore can flow upwardly into the lower end of the shoe through the spider openings 51 between the ribs 45 and through the valve housing 29. This fluid may shift the sleeve valve 33 in an upward direction away from engagement with the seat 38, whereupon it can continue flowing upwardly through the large diameter passage 52 through the sleeve valve, past the flapper valve head 19 and through the valve seat 18 for continued flowing into the casing sectionB above the shoe A. The ability of the fluid to flow upwardly in this manner is dependent upon the relative hydrostatic heads of fluid internally and externally of the casing string 8, which determines the engagement or non-engagement of the slidable sleeve valve member 33 with its companion seat 38. It is preferred that the fluid level in the casing string B remain at a substantially lower point than the external fluid level, to insure that the fluid entering the well casing will not overflow at its upper end and thereby wet the surface equipment and personnel.

To accomplish the aforementioned objective, the lower housing section 29 has an upper larger diameter cylindrical wall 53 and an adjacent lower cylindrical wall 54 of smaller internal diameter which are separated by the aforementioned stop shoulder 40. The slidable valve member 33 has a corresponding large diameter upper portion 55 adapted to slide along the upper Wall 53, and a smaller diameter portion 56 slidable along the lower cylindrical Wall 54. When the valve member 33 moves in a downward direction, to place its sealing edge 37 in engagement with the valve seat surface 57 on the head 41, for the purpose of preventing passage of fluid through the apparatus, the transverse shoulder 39 on the large diameter portion of the valve is disposed in spaced relation to and above the housing shoulder 40. At the same time, the tubular valve extension 34 is still in contact with the flapper valve head 19, to hold it to one side of the upper housing section 29 in a wide open position out of engagement from its seat 18.

Suitable slidable types of seals are provided between the cylindrical walls 53, 54 of the housing section 29 and the valve member 33. Thus, rubber or rubber-like seal rings 58, that may be of round cross-section, are disposed in one or more peripheral grooves 59 in the large and smaller diameter portions 55, 56 of the valve member 33 for slidable sealing with the companion large and smaller diameter cylindrical walls 53, 54 of the housing section. These seals 58 cooperate with the valve member 33 and the housing section 29 to form a confined annular cylindrical space 60 into which the well fluid cannot enter, this space containing air at substantially atmospheric pressure. v Since the smaller cylinder 54 has a lesser diameter than the larger cylinder 53, and the lower portion 56 of the valve member 33 has a corresponding lesser diameter than the diameter of the upper portion 55 of the valve member, the downwardly facing area R of the valve member over which fluid can act to urge the valve in an upward direc-' R to urge the valve member 33 in an upward direction out of engagement from its companion seat 38. The pressure of the fluid within the casing string B, which corresponds to the hydrostatic head of fluid therewithin is acting in a downward direction over the area S of the valve member 33, tending to urge the latter in a downward direction into engagement with the valve seat. A balanced condition on the valve 33 will be realized when the pressure acting upwardly on the valve member over the area R exerts a total force which is equal to the pressure acting on the valve member in the opposite direction over the area S. Since the area R is less than the area S, a balanced condition will be obtained when there is a lesser pressure internally of the casing string than exists externally thereof. Expressed by way of formula, a balanced condition will exist when:

P1R=P2S in which Pr=the hydrostatic head offluid externally of the casing string; and P2=the hydrostatic head of fluid internally of the well casing The hydrostatic heads of fluid externally and internally of the well casing will, therefore, be inversely proportional to the areas S and R. Since the area S is greater than the area R, the hydrostatic head of fluid internally of the well casing B will be less than the hydrostatic head of fluid externally of the well casing. As the hydrostatic head of fluid within the Well casing increases to a further extent, it will shift the valve member 33 downwardly into engagement with the valve seat 38, preventing further upward passage of fluid into the well casing B, until the casing string has been lowered in the well bore fluid to a further extent.

The apparatus is run in a well bore with the parts occupying the relative position disclosed in Fig. l. During such lowering, the hydrostatic head of fluid around the well casing B will act over the area R of the valve member 33 to shift it out of engagement from the valve seat 38, or to open position, allowing the fluid to flow upwardly around the valve seat 38, through the tubular valve member 33, passing past the wide open flapper valve head 19 and on into the casing string section B above the casing shoe A. If the casing string is brought to rest, as for the purpose of adding another casing section at the top of the hole, the fluid will flow therewithin until it rises to a level satisfying the aforenoted equation, and when the level tends to exceed the amount indicated by the equation, then the pressure of the fluid within the well casing will shift the valve member 33 downwardly into engagement with the valve seat 38, as disclosed in Fig. 2, thereby preventing further passage of fluid upwardly into the well casing. If the descent of the casing string in the well bore fluid is recommenced, the valve 33 will then slide upwardly to open position, as indicated in Fig. 1, and additional fluid will enter the casing string. The above actions will continue alternately, with the valve 33 shifting between open and closed positions until the casing has been lowered to the desired depth in the well bore. The level of the fluid in the well casing, however, will always be maintained at a lower point than the level of the fluid in the well bore externally of the well casing, depending upon the relationship of the aforenoted areas R and S. During all of this time, the upward extension 34 of the sleeve valve 33 is engaging the flapper valve head 19, to keep it in its fully open position and completely to one side of the fluid flowing upwardly through the sleeve valve 33, so as not to interfere therewith nor to be fluid cut thereby.

After the casing B has reached its desired depth in the well bore, the control valve mechanism C for determining the passage of fluid into the casing string, and the liquid level therein, is no longer needed. However, the back pressure valve member 19 should be released, so that it can thereafter perform its intended function. Accordingly, the casing string B can now be filled completely with fluid, which will urge and maintain the valve member 33 in a downward direction in sealing engagement with the valve seat 38. Pressure is then applied to the fluid in the well casing, this pressure acting downwardly on the sleeve valve member 33 and also downwardly over the valve seat 38. When the pressure is sufiicient to exceed the shear strength of the pins 46, the latter are disrupted, allowing the valve seat 38 to shift downwardly until its head 41 engages the upper end of the hub 43, the sleeve valve 33 shifting downwardly into engagement with the housing shoulder 40 (Fig. 3). Since the valve seat 38 shifts downwardly to a much greater extent than the valve member 33, it moves out of engagement from the sleeve valve member 33 to a considerable extent, leaving a large passage area therebetween. .At the same time, the engagement of the sleeve valve member 33 with the housing shoulder 40 places its upward extension 34 completely out of engagement with the flapper valve head 19, allowing the spring 23 to shift the flapper valve .head upwardly into engagement with its companion seat 18 and seal ring 26.

Any further upward flow of fluid into the'well casing through the apparatus is then precluded because of the engagement of the flapper valve head 19 with its companion seat 18. However, fluid can be pumped down the casing string, forcing the flapper valve head to one side, and continuing to flow on down through the sleeve valve member 33, and between the latter and the valve seat 38, for passage through the spider ports 51 and discharge 6. from the lower end of the casing shoe passage 17' (Fig. 3"). Thus, circulating fluid may be pumped down the casing string to condition the well bore, whereupon a charge of cement slurry, if the casing string is to be cemented in the well bore, can be pumped down the casing string, passing completely through the casing shoe A and then upwardly through the annulus between the. casing string and the wall of the well bore. When the pressure within the well casing B is relieved, any tendency for the cement slurry to flow back into the casing string is precluded by the closing of the flapper valve head 19 against its companion seat 18.

It is to be noted that the flapper valve head 19 is maintained in a fully open position during lowering of the casing string B in the well bore, and completely out of the path of flow of the fluid passing upwardly through the apparatus. Accordingly, the danger of the flapper valve head being fluid cut or eroded by thewell bore fluid is minimized, if not completely eliminated. Accordingly, when the flapper valve head 19 is released, assurance is had that it will engage its companion seat 18 in leakproof fashion.

The arrangement of parts for controllably filling the well casing with the well bore fluid and maintaining the back pressure valve member inoperative until it is purposely released provides a comparatively short over-all apparatus, one which possesses fewer parts, all of which makes the apparatus more economical to manufacture than other corresponding devices.

As was stated above, the relationship between the areas R and S of the downward and upwardly facing pressure actuatable surfaces of the valve member 33 determines the level to which the fluid in the well casing can rise with respect to the fluid level externally of the casing string. If these areas are made equal, then the well casing string B will be able to fill with the well bore fluid to a level equalling that of the fluid externally of the well casing. However, it is preferred to provide the differential area relationship noted above, since assurance is then had that the well bore fluid will not overflow the casing string at the top of the hole.

The use of the differential valve mechanism C assures the rapid filling of the casing string with the well bore fluid as it is being lowered therewithin. However, after the casing string has reached its predetermined location in the well bore, it is still necessary to fill the remainder of the casing string with the well bore fluid before the automatic filling apparatus can be rendered ineffective and the back pressure valve member 19 released. The necessity for so filling the conduit string from the top of the hole can be eliminated, if desired. As disclosed in the drawings, the valve seat 38 may have a central passage or orifice 70 extending completely therethrough. This orifice has a comparatively small area, and, accordingly, fluid can flow upwardly therethrough at a very slow volumetric rate. This orifice passage or by-pass 70 is always open, to permit upward flow of fluid when the flapper valve member 19 is held in open position. Accordingly, fluid is constantly flowing through it. During lowering of the casing string B in the well bore, the sleeve valve member 33 will be shifted upwardly to open position, to allow a rapid filling of the casing string to the predetermined level, which is lower than the fluid level externally of the casing string. When this level has been reached and the sleeve valve 33 is shifted down-v wardly to its closed position, then theremainder of the casing string can be filled with fluid in a rather slow fashion, because of the path provided by the orifice 70. Such filling action continues while the casing string is .at rest, as occurs when another section of casing is being attached at the top of the well bore. The rate at which the fluid can flow through the orifice 70, however, is relatively small, so that in the ordinary case the casing string is still not completely filled with fluid by the time the next casing section has been attached to the string and the latter again lowered through the fluid in the well bore. Accordingly, the sleeve valve 33 is again shifted upwardly to open position to allow a rapid filling of the well bore fluid, the sleeve valve 33 then closing when the predetermined internal fluid level is reached, the fluid then continuing to flow into the casing string in a cornparatively slow manner through the open orifice 70.

By the time the casing string has been run in the well bore to the desired depth, the fluid level therewithin has almost reached its upper end. Instead of it being necessary to fill the casing string through the top of the hole, the level will rise gradually by virtue of the passage of the fluid into the casing strings through the orifice 70. Since such passage occurs in a slow manner, there is little likelihood of the fluid overflowing the well casing at the top of the hole, and accordingly, the equipment and personnel is not drenched with the fluid, as oftentimes occurs when wide open casing strings are lowered through the fluid in the well bore.

The orifice 71') is of such restricted area that it does not preclude the building up of a sutficient back pressure on the sleeve valve 33 and the valve seat 38 when the shear pins 46 are to be disrupted. However, if the orifice area is made sufiiciently large, or if assurance is desired that sufficient pressure can be built up to render the automatic filling portion C of the device inoperative, the orifice 70 can be closed against downward passage of fluid. As disclosed, the upper portion of the valve seat 38 may be provided with an enlarged passage or counterbore 71 in which a'valve element 72, such as a ball, is disposed. This ball 72 can move downwardly into engagement with a companion seat '73 at the upper end of the orifice 70, to preclude downward passage of fluid therethrough. However, the ball 72 moves in an upward direction away from its companion seat 73 whenever fluid is flowing upwardly through the orifice 70, so as not to interfere with such upward flow of fluid. Loss of the ball 72 from the enlarged passage portion 71 of the valve head 38 may be precluded by a suitable retainer member disposed thereabove, such as the pin 74 secured to the valve head 41 and extending transversely across the enlarged passage 71.

When pressure is to be applied to the fluid within the well casing, the ball 72 will move downwardly into engagement with its seat 73, whereupon the full pressure is effective over the sleeve valve 33 and the valve seat 38, to shear the pins 46 and secure the downward shifting of the sleeve valve 33 out of engagement with the flapper valve member 19, and the downward movement of the valve seat 38 away from the sleeve valve 33.

The inventor claims:

1. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a valve seat in said tubular member; a valve member pivotally mounted in said tubular member and movable upwardly into engagement with Said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member, said device engaging said valve member to prevent its engagement with said seat; and releasable means engageable with said valve device and connected to said tubular member to hold said device in engagement with said valve member, said means being releasable to allow said valve device to be shifted downwardly in said tubular member out of engagement with said valve member to allow said valve member to engage said seat.

2. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a valve seat in said tubular member; a valve member pivotally mounted in said tubular member and movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of-flu'id in said tubular member, said device being mounted in said tubular member be low said valve member and including a tubular part engaging said valve member to hold said valve member in a fully open position out of engagement with said seat and substantially entirely out of the path of fluid flowing upwardly through said tubular part and said seat; and releasable means engageable with said valve device and connected to said tubular member to hold said tubular part in engagement with said valve member, said means being releasable to allow said valve device to be shifted downwardly in said tubular member to lower and withdraw said tubular part from engagement with said valve member to allow said valve member to engage said seat.

3. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member; a valve head pivotally mounted in said tubular member and movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member, said device including a second valve seat in said tubular member and a valve member movable downwardly into engagement with said second seat; holding means secured to said valve member and engaging said valve head to hold said head in open position while said valve member engages said second seat and also while said valve member is elevated from said second seat; and releasable means connected to said tubular member for maintaining said valve member in a position in which said holding means is in engagement with said head, said releasable means being released to allow said valve member to be shifted downwardly to a position withdrawing said holding means from said valve head to allow said valve head to engage said first valve seat.

4. In Well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member; a first valve member in said tubular member and movable upwardly into engagement with said first valve seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member, said device including a second valve seat in said tubular member and a second valve member movable downwardly into engagement with said second seat; holding means secured to said second valve member and engaging said first valve member to hold said first valve member in open position and substantially completely out of the path of fluid flowing through said first valve seat; said holding means engaging said first valve member while saidsecond valve member engages said second seat and also while said second valve member is elevated from said second seat; and releasable means connected to said tubular member for maintaining said second valve member in a position'in which said holding means engages said first valve member, release of said releasable means allowing said second valve member to be shifted downwardly to a position withdrawing said holding means from said first valve member to allow said first valve member to engage said first valve seat.

5. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member; a first valve member in said tubular member movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member, said device including a second valve seat in said tubular member and a tubular valve member movable downwardly into engagement with said second seat; holding means secured to said tubular valve member and engaging said first valve member to hold said first valve member in open position while said tubular valve member engages said second seat and also while said tubular valve member is elevated from said'second seat; and means releasably securing said second valve seat to said tubular member to enable said tubular valve member and seat to be shifted downwardly to a position withdrawing said holding means from said first valve member to allow saidfirst valve member to engage said first valve seat.

6. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member; a first valve member in said tubular member movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member, said device including a second valve seat in said tubular member and a tubular valve member movable downwardly into engagement with said second seat; holding means secured to said tubular valve member and engaging said first valve member to hold said first valve member in open position while said tubular valve member engages said second seat and also while said tubular member is ele vated from said second seat; frangible means releasably securing said second valve seat to said tubular member and disruptable by fluid under pressure above and acting on said second seat to allow said second seat and tubular valve member to move downwardly to a position in which said holding means is withdrawn from its position holding said first valve member in open position.

7. In well apparatus: a tubular member having means thereon for secun'ng said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member; a first valve member in said tubular member movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member, said device including a second valve seat in said tubular member and a second tubular valve member movable downwardly into engagement with said second seat; a tubular extension secured to said tubular valve member and engaging said first valve member to hold said first valve member in a fully open position out of engagement with said first seat and substantially completely out of the path of fluid flowing upwardly through said tubular extension and said first valve seat, said tubular extension holding said first valve member in such open position while said tubular valve member engages said second seat and also while said tubular valve member is elevated from said second seat; and releasable means connected to said tubular member for maintaining said second tubular valve member in a position in which said tubular extension engages said first valve member, release of said releasable means allowing said tubular valve member to be shifted downwardly to a position withdrawing said tubular extension from said first valve member to allow said first valve member to engage said first valve seat.

8. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a valve seat in said tubular member; a valve member pivotally mounted in said tubular member and movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member and into the conduit string to a predetermined level that is lower than the level of the well bore fluid surrounding the conduit string, said valve device closing when said predetermined level is reached, said device engaging said valve member to prevent its engagement with said seat; by-pass means to allow restricted upward flow of fluid within said tubular member past said valve device when said valve device is closed; and releasable means engageable with said valve member and connected to said tubular member to hold said device in engagement with said valve member, said means being releasable to allow said valve device to be shifted downwardly in said tubular member out of engagement with said valve member to allow said valve member to engage said seat.

9. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a valve seat in said tubular member; a valve member in said tubular member and 1O movable upwardly into engagement with said'seat;-a' valve device in said tubular member for allowing upward flow of fluid in said tubular member and into the conduit string to a predetermined level that is lower than the level of well bore fluid externally of the conduit string, said valve device closing when said predetermined level is reached, said device engaging said valve member to prevent its engagement with said seat; by-pass orifice means to allow restricted upward flow of fluid within said tubular member past said valve device when said valve device is closed; and releasable means engageable with said valve device and connected to said tubular member to hold said device in engagement with said valve member, said means being releasable to allow said valve device to be shifted downwardly in said tubular member out of engagement with said valve member to allow said valve member to engage said seat. I

10. In well apparatus; a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a valve seat in said tubular member; a valve member in said tubular member and movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member and into the conduit string to a predetermined level that is lower than the level of well bore fluid externally of the conduit string, said valve device closing when said predetermined level is reached, said device engaging said valve member to prevent its engagement with said seat; by-pass orifice means to allow restricted upward flow of fluid within said tubular member past said valve device when said valve device is closed; releasable means engageable with said valve device and connected to said tubular member to hold said device in engagement with said valve member, said means being releasable to allow said valve device to be shifted downwardly in said tubular member out of engagement with said valve member to allow said valve member to engage said seat; and valve means for closing said by-pass orifice means against downward flow of fluid therethrough.

11. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member; a first valve member in said tubular member and movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member and into the conduit string to a predetermined level that is lower than the level of well bore fluid surrounding the conduit string, said device including a second valve seat in said tubular member and a second valve member movable downwardly into engagement with said second seat; holding means secured to said second valve member and engaging said first valve member to hold said first valve member in open position while said second valve member engages said second seat and also while said second valve member is elevated from said second seat; said second valve seat having a by-pass orifice therethrough to allow restricted upward flow of fluid within said tubular member past said valve device when said second valve member engages said second valve seat; and releasable means connected to said tubular member for maintaining said second valve member in a position in which said holding means engages said first valve member, release of said releasable means allowing said second valve member to be shifted downwardly to a position withdrawing said holding means from said first valve member to allow said first valve member to engage said first valve seat.

12. In well apparatus: a tubular member having means thereon for securing said member in a conduit string to be lowered in a well bore; a first valve seat in said tubular member, a first valve member in said tubular memher and movable upwardly into engagement with said seat; a valve device in said tubular member for allowing upward flow of fluid in said tubular member and into the conduit string to a predetermined level that is lower than the level of well bore fluid surrounding the conduit string, said device including a second valve seat in said tubular member and a second valve member movable downwardly into engagement with said second seat; holding means secured to said second valve member and engaging said first valve member to hold said first valve member in open position while said second valve member engages said second seat and also while said second valve member is elevated from said second seat; said second valve seat having a by-pass orifice therethrough to allow restricted upward flow of fluid within said tubular member past said valve device when said second valve member engages said second valve seat; releasable means connected to said tubular member for maintaining said second valve member in a position in which said holding means engages said first valve member, release of said releasable means allowing said second valve member to be shifted downwardly to a position withdrawing said holding means from said first valve member to allow said first valve member to engage said first valve seat; and valve means movable downwardly into engagement with said second valve seat to close said by-pass orifice against downward flow of fluid therethrough.

References Cited in the file of this patent UNlTED STATES PATENTS 2,162,578 Hacker June 13, 1939 2,351,873 Parker June 20, 1944 FOREIGN PATENTS 56,152 Denmark May 8, 1939 

1. IN WELL APPARATUS: A TUBULAR MEMBER HAVING MEANS THEREON FOR SECURING SAID MEMBER IN A CONDUIT STRING TO BE LOWERED IN A WELL BORE; A VALVE SEAT IN SAID TUBULAR MEMBER; A VALVE MEMBER PIVOTALLY MOUNTED IN SAID TUBULAR MEMBER AND MOVABLE UPWARDLY INTO ENGAGEMENT WITH SAID SEAT; A VALVE DEVICE IN SAID TUBULAR MEMBER FOR ALLOWING UPWARD FLOW OF FLUID IN SAID TUBULAR MEMBER, SAID DEVICE ENGAGING SAID VALVE MEMBER TO PREVENT ITS ENGAGEMENT WITH SAID SEAT; AND RELEASABLE MEANS ENGAGEABLE WITH SAID VALVE DEVICE AND CONNECTED TO SAID TUBULAR MEMBER TO HOLD SAID DEVICE IN ENGAGEMENT WITH SAID VALVE MEMBER, SAID MEANS BEING RELEASABLE TO ALLOW SAID VALVE DEVICE TO BE SHIFTED DOWNWARDLY IN SAID TUBULAR MEMBER OUT OF ENGAGEMENT WITH SAID VALVE MEMBER TO ALLOW SAID VALVE MEMBER TO ENGAGE SAID SEAT. 